Methods and apparatus for packet acquisition in mixed-rate wireless communication networks

ABSTRACT

A method of wirelessly communicating a packet includes generating, at a first wireless device, a first packet including a first preamble decodable by a plurality of devices and a second preamble decodable by only a subset of the plurality of devices. The first preamble includes a first signal field. The second preamble includes a first training field. The method further includes transmitting the first packet concurrently with one or more second packets to be transmitted by wireless devices other than the first wireless device.

PRIORITY CLAIM

This application claims the benefit of U.S. Provisional Application No.62/053,062, filed Sep. 19, 2014, and U.S. Provisional Application No.62/104,626, filed Jan. 16, 2015, and U.S. Provisional Application No.62/106,075, filed Jan. 21, 2015, each of which are hereby incorporatedherein by reference in its entirety.

FIELD

Certain aspects of the present disclosure generally relate to wirelesscommunications, and more particularly, to methods and apparatus formixed-rate communication in a wireless network.

BACKGROUND

In many telecommunication systems, communications networks are used toexchange messages among several interacting spatially-separated devices.Networks can be classified according to geographic scope, which couldbe, for example, a metropolitan area, a local area, or a personal area.Such networks can be designated respectively as a wide area network(WAN), metropolitan area network (MAN), local area network (LAN), orpersonal area network (PAN). Networks also differ according to theswitching/routing technique used to interconnect the various networknodes and devices (e.g., circuit switching vs. packet switching), thetype of physical media employed for transmission (e.g., wired vs.wireless), and the set of communication protocols used (e.g., Internetprotocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).

Wireless networks are often preferred when the network elements aremobile and thus have dynamic connectivity needs, or if the networkarchitecture is formed in an ad hoc, rather than fixed, topology.Wireless networks employ intangible physical media in an unguidedpropagation mode using electromagnetic waves in the radio, microwave,infrared, optical, etc. frequency bands. Wireless networksadvantageously facilitate user mobility and rapid field deployment whencompared to fixed wired networks.

As the volume and complexity of information communicated wirelesslybetween multiple devices continues to increase, overhead bandwidthrequired for physical layer control signals continues to increase atleast linearly. The number of bits utilized to convey physical layercontrol information has become a significant portion of requiredoverhead. Thus, with limited communication resources, it is desirable toreduce the number of bits required to convey this physical layer controlinformation, especially as multiple types of traffic are concurrentlysent from an access point to multiple terminals. For example, when awireless device sends low-rate uplink communications to an access point,it is desirable to minimize the number of bits used for signaling andpacket acquisition while maintaining backwards compatibility. Thus,there is a need for an improved protocol for mixed-rate transmissions.

SUMMARY

Various implementations of systems, methods and devices within the scopeof the appended claims each have several aspects, no single one of whichis solely responsible for the desirable attributes described herein.Without limiting the scope of the appended claims, some prominentfeatures are described herein.

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages can becomeapparent from the description, the drawings, and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

One aspect of the present disclosure provides a method of wirelesscommunication. The method includes generating, at a first wirelessdevice, a first packet including a first preamble decodable by aplurality of devices and a second preamble decodable by only a subset ofthe plurality of devices. The first preamble includes a first signalfield. The second preamble includes a first training field. The methodfurther includes transmitting the first packet concurrently with one ormore second packets to be transmitted by wireless devices other than thefirst wireless device.

In various embodiments, the method can further include transmitting thefirst signal field over a channel bandwidth up to a full channelbandwidth size assigned to the first wireless device. In variousembodiments, the method can further include, when the first wirelessdevice is not assigned use of a channel designated as a primary channel,transmitting the first signal field over the channel designated as theprimary channel. In various embodiments, the method can further includetransmitting the first signal field over an available channel bandwidthincluding one or more channels not assigned for use by the firstwireless device. In various embodiments, the available channel bandwidthcan be an entirety of the available channel bandwidth.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a common zone with the first wirelessdevice. The method can further include setting the first signal field toindicate a length of the first packet equal to a length of a longest ofthe at least one second packet to be transmitted by the second wirelessdevice assigned to the common zone with the first wireless device. Themethod can further include padding the first packet for transmission toequal the length of the longest of the at least one second packet to betransmitted by the second wireless device assigned to the common zonewith the first wireless device.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a different zone from the first wirelessdevice. The method can further include setting the first signal field toindicate a length of the first packet equal to a length of a longest ofthe at least one second packet to be transmitted by the second wirelessdevice being assigned to any zone including a commonly assigned zonewith the first wireless device. The method can further include paddingthe first packet for transmission to equal the length of the longest ofthe at least one second packet to be transmitted by the second wirelessdevice being assigned to any zone including a commonly assigned zonewith the first wireless device.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device. The method can further include the method can furtherinclude refraining from padding the first packet. In variousembodiments, the second preamble can further include a second signalfield.

In various embodiments, the second preamble can further include a secondsignal field that is one symbol in length. In various embodiments, thesecond preamble can further include a full or partial repetition of thefirst signal field, and a second signal field. In various embodiments,the method can further include encoding one or more bits in a polarityof the full or partial repetition of the first signal field.

In various embodiments, the second preamble can further include arepetition of even or odd tones of the first signal field, and a secondsignal field. In various embodiments, the second preamble can furtherinclude a second signal field and a repetition of the second signalfield. In various embodiments, the second preamble can further include asecond training field, the second training field shorter than the firsttraining field.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby the second wireless device assigned to the common zone with the firstwireless device. The method can further include padding the firsttraining field to align a boundary of all training fields to betransmitted by the second wireless device assigned to the common zonewith the first wireless device.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device being assigned to any zone including acommonly assigned zone with the first wireless device. The method canfurther include padding the first training field to align a boundary ofall training fields to be transmitted by a second wireless device beingassigned to any zone including a commonly assigned zone with the firstwireless device.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device. The method can further include refrainingfrom padding the first training field. In various embodiments, thesecond preamble can further include a second signal field, and mayfurther comprise a repetition of the second signal field based, at leastin part, on one of: a protection method used for a third signal field ofthe second portion; a compression method used for the first trainingfield; and a prefix of a payload of the first packet.

In various embodiments, the first signal field can include an immediateresponse presence and/or duration indication. In various embodiments,the first signal field can include a transmit power indication. Invarious embodiments, the first signal field can include a partial timesynchronization function (TSF).

In various embodiments, the first signal field can include a transmitopportunity (TXOP) bandwidth (BW) and/or primary channel offsetindication. In various embodiments, the first signal field can include apartial base station identifier (BSSID). In various embodiments, thefirst signal field can include a partial receiver association identifier(AID).

In various embodiments, the first signal field can include a partialtransmitter association identifier (AID). In various embodiments, thefirst signal field can include an uplink/downlink indication. In variousembodiments, the uplink/downlink indication can be implicit in atransmitter or receiver association identifier (AID).

Another aspect provides an apparatus configured to wirelesslycommunicate. The apparatus includes a processor configured to generate afirst packet including a first preamble decodable by a plurality ofdevices and a second preamble decodable by only a subset of theplurality of devices. The first preamble includes a first signal field.The second preamble includes a first training field. The apparatusfurther includes a transmitter configured to transmit the first packetconcurrently with one or more second packets to be transmitted bywireless devices other than the apparatus.

In various embodiments, the transmitter can be further configured totransmit the first signal field over a channel bandwidth up to a fillchannel bandwidth size assigned to the apparatus. In variousembodiments, the transmitter can be further configured to, when theapparatus is not assigned a primary channel, transmit the first signalfield over the channel designated as the primary channel. In variousembodiments, the transmitter can be further configured to transmit thefirst signal field over an available channel bandwidth including one ormore channels not assigned to the apparatus. In various embodiments, theavailable channel bandwidth can be an entirety of the available channelbandwidth.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a common zone with the apparatus. Theprocessor can be further configured to set the first signal field toindicate a length of the first packet equal to a length of a longest ofthe at least one second packet to be transmitted by a second wirelessdevice assigned to a common zone with the apparatus. In variousembodiments, the processor can be further configured to pad the firstpacket to equal the length of the longest of the at least one secondpacket to be transmitted by a second wireless device assigned to acommon zone with the apparatus.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a different zone from the apparatus. Theprocessor can be further configured to set the first signal field toindicate a length of the first packet equal to a length of a longest ofthe at least one second packet to be transmitted by the second wirelessdevice being assigned to any zone including a commonly assigned zonewith the apparatus. In various embodiments, the processor can be furtherconfigured to pad the first packet to equal the length of the longest ofthe at least one second packet to be transmitted by the second wirelessdevice being assigned to any zone including a commonly assigned zonewith the apparatus.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device. The processor can be further configured to refrain frompadding the first packet. In various embodiments, the second preamblecan further include a second signal field.

In various embodiments, the second preamble can further include a secondsignal field that is one symbol in length. In various embodiments, thesecond preamble can further include a full or partial repetition of thefirst signal field, and a second signal field. In various embodiments,the processor can be further configured to encode one or more bits in apolarity of the full or partial repetition of the first signal field.

In various embodiments, the second preamble can further include arepetition of even or odd tones of the first signal field, and a secondsignal field. In various embodiments, the second preamble can furtherinclude a second signal field and a repetition of the second signalfield. In various embodiments, the second preamble can further include asecond training field, the second training field shorter than the firsttraining field.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device assigned to a common zone with theapparatus. The processor can be further configured to pad the firsttraining field to align a boundary of all training fields to betransmitted by the second wireless device assigned to the common zonewith the apparatus.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device being assigned to any zone including acommonly assigned zone with the apparatus. The processor can be furtherconfigured to pad the first training field to align a boundary of alltraining fields to be transmitted by a second wireless device beingassigned to any zone including a commonly assigned zone with theapparatus.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device. The processor can be further configured torefrain from padding the first training field. In various embodiments,the second preamble can further include a second signal field, and mayfurther comprise a repetition of the second signal field based, at leastin part, on one of: a protection method used for a third signal field ofthe second portion; a compression method used for the first trainingfield; and a prefix of a payload of the first packet.

In various embodiments, the first signal field can include an immediateresponse presence and/or duration indication. In various embodiments,the first signal field can include a transmit power indication. Invarious embodiments, the first signal field can include a partial timesynchronization function (TSF).

In various embodiments, the first signal field can include a transmitopportunity (TXOP) bandwidth (BW) and/or primary channel offsetindication. In various embodiments, the first signal field can include apartial base station identifier (BSSID). In various embodiments, thefirst signal field can include a partial receiver association identifier(AID).

In various embodiments, the first signal field can include a partialtransmitter association identifier (AID). In various embodiments, thefirst signal field can include an uplink/downlink indication. In variousembodiments, the uplink/downlink indication can be implicit in atransmitter or receiver association identifier (AID).

Another aspect provides another apparatus for wireless communication.The apparatus includes means for generating a first packet including afirst preamble decodable by a plurality of devices and a second preambledecodable by only a subset of the plurality of devices. The firstpreamble includes a first signal field. The second preamble includes afirst training field. The apparatus further includes means fortransmitting the first packet concurrently with one or more secondpackets to be transmitted by wireless devices other than the apparatus.

In various embodiments, the apparatus can further include means fortransmitting the first signal field over a channel bandwidth up to afill channel bandwidth size assigned to the apparatus. In variousembodiments, the apparatus can further include means for, when theapparatus is not assigned a primary channel, transmitting the firstsignal field over the channel designated as the primary channel. Invarious embodiments, the apparatus can further include means fortransmitting the first signal field over an available channel bandwidthincluding one or more channels not assigned to the apparatus. In variousembodiments, the available channel bandwidth can be an entirety of theavailable channel bandwidth.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a common zone with the apparatus. Theapparatus can further include means for setting the first signal fieldto indicate a length of the first packet equal to a length of a longestof the at least one second packet to be transmitted by a second wirelessdevice assigned to a common zone with the apparatus. The apparatus canfurther include means for padding the first packet for transmission toequal the length of the longest of the at least one second packet to betransmitted by a second wireless device assigned to a common zone withthe apparatus.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a different zone from the apparatus. Theapparatus can further include means for setting the first signal fieldto indicate a length of the first packet equal to a length of a longestof the at least one second packet to be transmitted by the secondwireless device being assigned to any zone including a commonly assignedzone with the apparatus. The apparatus can further include means forpadding the first packet for transmission to equal the length of thelongest of the at least one second packet to be transmitted by thesecond wireless device being assigned to any zone including a commonlyassigned zone with the apparatus.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device. The apparatus can further include means for refrainingfrom padding the first packet. In various embodiments, the secondpreamble can further include a second signal field.

In various embodiments, the second preamble can further include a secondsignal field that is one symbol in length. In various embodiments, thesecond preamble can further include a full or partial repetition of thefirst signal field, and a second signal field. In various embodiments,the apparatus can further include means for encoding one or more bits ina polarity of the full or partial repetition of the first signal field.

In various embodiments, the second preamble can further include arepetition of even or odd tones of the first signal field, and a secondsignal field. In various embodiments, the second preamble can furtherinclude a second signal field and a repetition of the second signalfield. In various embodiments, the second preamble can further include asecond training field, the second training field shorter than the firsttraining field.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device assigned to a common zone with theapparatus. The apparatus can further include means for padding the firsttraining field to align a boundary of all training fields to betransmitted by the second wireless device assigned to the common zonewith the apparatus.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device being assigned to any zone including acommonly assigned zone with the apparatus. The apparatus can furtherinclude means for padding the first training field to align a boundaryof all training fields to be transmitted by a second wireless devicebeing assigned to any zone including a commonly assigned zone with theapparatus.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device. The apparatus can further include means forrefraining from padding the first training field. In variousembodiments, the second preamble can further include a second signalfield, and may further comprise a repetition of the second signal fieldbased, at least in part, on one of: a protection method used for a thirdsignal field of the second portion; a compression method used for thefirst training field; and a prefix of a payload of the first packet.

In various embodiments, the first signal field can include an immediateresponse presence and/or duration indication. In various embodiments,the first signal field can include a transmit power indication. Invarious embodiments, the first signal field can include a partial timesynchronization function (TSF).

In various embodiments, the first signal field can include a transmitopportunity (TXOP) bandwidth (BW) and/or primary channel offsetindication. In various embodiments, the first signal field can include apartial base station identifier (BSSID). In various embodiments, thefirst signal field can include a partial receiver association identifier(AID).

In various embodiments, the first signal field can include a partialtransmitter association identifier (AID). In various embodiments, thefirst signal field can include an uplink/downlink indication. In variousembodiments, the uplink/downlink indication can be implicit in atransmitter or receiver association identifier (AID).

Another aspect provides a non-transitory computer-readable medium. Themedium includes code that, when executed, causes an apparatus togenerate a first packet including a first preamble decodable by aplurality of devices and a second preamble decodable by only a subset ofthe plurality of devices. The first preamble includes a first signalfield. The second preamble includes a first training field. The mediumfurther includes code that, when executed, causes the apparatus totransmit the first packet concurrently with one or more second packetsto be transmitted by wireless devices other than the apparatus.

In various embodiments, the apparatus can further include code that,when executed, causes the apparatus to transmit the first signal fieldover a channel bandwidth up to a fill channel bandwidth size assigned tothe apparatus. In various embodiments, the apparatus can further includecode that, when executed, causes the apparatus to, when the apparatus isnot assigned a primary channel, transmit the first signal field over thechannel designated as the primary channel. In various embodiments, theapparatus can further include code that, when executed, causes theapparatus to transmit the first signal field over an available channelbandwidth including one or more channels not assigned to the apparatus.In various embodiments, the available channel bandwidth can be anentirety of the available channel bandwidth.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a common zone with the apparatus. The mediumfurther includes code that, when executed, causes the apparatus to setthe first signal field to indicate a length of the first packet equal toa length of a longest of the at least one second packet to betransmitted by a second wireless device assigned to a common zone withthe apparatus. In various embodiments, the apparatus can further includecode that, when executed, causes the apparatus to pad the first packetto equal the length of the longest of the at least one second packet tobe transmitted by a second wireless device assigned to a common zonewith the apparatus.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a different zone from the apparatus. Themedium further includes code that, when executed, causes the apparatusto further including code that, when executed, causes the apparatus toset the first signal field to indicate a length of the first packetequal to a length of a longest of the at least one second packet to betransmitted by the second wireless device being assigned to any zoneincluding a commonly assigned zone with the apparatus. In variousembodiments, the apparatus can further include code that, when executed,causes the apparatus to pad the first packet to equal the length of thelongest of the at least one second packet to be transmitted by thesecond wireless device being assigned to any zone including a commonlyassigned zone with the apparatus.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device. The medium further includes code that, when executed,causes the apparatus to refrain from padding the first packet. Invarious embodiments, the second preamble can further include a secondsignal field.

In various embodiments, the second preamble can further include a secondsignal field that is one symbol in length. In various embodiments, thesecond preamble can further include a full or partial repetition of thefirst signal field, and a second signal field. In various embodiments,the medium can further include code that, when executed, causes theapparatus to encode one or more bits in a polarity of the full orpartial repetition of the first signal field.

In various embodiments, the second preamble can further include arepetition of even or odd tones of the first signal field, and a secondsignal field. In various embodiments, the second preamble can furtherinclude a second signal field and a repetition of the second signalfield. In various embodiments, the second preamble can further include asecond training field, the second training field shorter than the firsttraining field.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device assigned to a common zone with theapparatus. The medium further includes code that, when executed, causesthe apparatus to pad the first training field to align a boundary of alltraining fields to be transmitted by the second wireless device assignedto the common zone with the apparatus.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device being assigned to any zone including acommonly assigned zone with the apparatus. The medium further includescode that, when executed, causes the apparatus to pad the first trainingfield to align a boundary of all training fields to be transmitted by asecond wireless device being assigned to any zone including a commonlyassigned zone with the apparatus.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device. The medium further includes code that, whenexecuted, causes the apparatus to refrain from padding the firsttraining field. In various embodiments, the second preamble can furtherinclude a second signal field, and may further comprise a repetition ofthe second signal field based, at least in part, on one of: a protectionmethod used for a third signal field of the second portion; acompression method used for the first training field; and a prefix of apayload of the first packet.

In various embodiments, the first signal field can include an immediateresponse presence and/or duration indication. In various embodiments,the first signal field can include a transmit power indication. Invarious embodiments, the first signal field can include a partial timesynchronization function (TSF).

In various embodiments, the first signal field can include a transmitopportunity (TXOP) bandwidth (BW) and/or primary channel offsetindication. In various embodiments, the first signal field can include apartial base station identifier (BSSID). In various embodiments, thefirst signal field can include a partial receiver association identifier(AID).

In various embodiments, the first signal field can include a partialtransmitter association identifier (AID). In various embodiments, thefirst signal field can include an uplink/downlink indication. In variousembodiments, the uplink/downlink indication can be implicit in atransmitter or receiver association identifier (AID).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communication system inwhich aspects of the present disclosure can be employed.

FIG. 2 illustrates various components that can be utilized in a wirelessdevice that can be employed within the wireless communication system ofFIG. 1.

FIG. 3 illustrates a channel allocation for channels available for802.11 systems.

FIGS. 4 and 5 illustrate data packet formats for several currentlyexisting Institute of Electrical and Electronics Engineers (IEEE) 802.11standards.

FIG. 6 illustrates a frame format for the currently existing IEEE802.11ac standard.

FIG. 7 illustrates an exemplary structure of a physical-layer packetwhich can be used to enable backward-compatible multiple access wirelesscommunications.

FIG. 8 illustrates an exemplary structure of an uplink or downlinkphysical-layer packet which can be used to enable wirelesscommunications.

FIG. 9A illustrates an exemplary structure of an uplink physical-layerpacket which can be used to enable wireless communications.

FIG. 9B illustrates another exemplary structure of an uplinkphysical-layer packet which can be used to enable wirelesscommunications.

FIG. 9C illustrates another exemplary structure of an uplinkphysical-layer packet which can be used to enable wirelesscommunications.

FIG. 9D illustrates another exemplary structure of an uplinkphysical-layer packet which can be used to enable wirelesscommunications.

FIG. 9E illustrates another exemplary structure of an uplinkphysical-layer packet which can be used to enable wirelesscommunications.

FIG. 10 illustrates another exemplary structure of an uplinkphysical-layer packet which can be used to enable wirelesscommunications.

FIG. 11 shows another flowchart for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem of FIG. 1.

DETAILED DESCRIPTION

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully hereinafter with reference to the accompanyingdrawings. The teachings disclosed can, however, be embodied in manydifferent forms and should not be construed as limited to any specificstructure or function presented throughout this disclosure. Rather,these aspects are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the disclosure to thoseskilled in the art. Based on the teachings herein one skilled in the artshould appreciate that the scope of the disclosure is intended to coverany aspect of the novel systems, apparatuses, and methods disclosedherein, whether implemented independently of or combined with any otheraspect of the invention. For example, an apparatus can be implemented ora method can be practiced using any number of the aspects set forthherein. In addition, the scope of the invention is intended to coversuch an apparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to or otherthan the various aspects of the invention set forth herein. It should beunderstood that any aspect disclosed herein can be embodied by one ormore elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

Wireless network technologies can include various types of wirelesslocal area networks (WLANs). A WLAN can be used to interconnect nearbydevices together, employing widely used networking protocols. Thevarious aspects described herein can apply to any communicationstandard, such as WiFi or, more generally, any member of the IEEE 802.11family of wireless protocols. For example, the various aspects describedherein can be used as part of an IEEE 802.11 protocol, such as an 802.11protocol which supports orthogonal frequency-division multiple access(OFDMA) communications.

It can be beneficial to allow multiple devices, such as stations (STAs),to communicate with an AP at the same time. For example, this can allowmultiple STAs to receive a response from the AP in less time, and to beable to transmit and receive data from the AP with less delay. This canalso allow an AP to communicate with a larger number of devices overall,and can also make bandwidth usage more efficient. By using multipleaccess communications, the AP can be able to multiplex orthogonalfrequency-division multiplexing (OFDM) symbols to, for example, fourdevices at once over an 80 MHz bandwidth, where each device utilizes 20MHz bandwidth. Thus, multiple access communications can be beneficial insome aspects, as it can allow the AP to make more efficient use of thespectrum available to it.

It has been proposed to implement such multiple access protocols in anOFDM system such as the 802.11 family by assigning different subcarriers(or tones) of symbols transmitted between the AP and the STAs todifferent STAs. In this way, an AP could communicate with multiple STAswith a single transmitted OFDM symbol, where different tones of thesymbol were decoded and processed by different STAs, thus allowingsimultaneous data transfer to multiple STAs. These systems are sometimesreferred to as OFDMA systems.

Such a tone allocation scheme is referred to herein as a“high-efficiency” (HE) system, and data packets transmitted in such amultiple tone allocation system can be referred to as high-efficiency(HE) packets. Various structures of such packets, including backwardcompatible preamble fields are described in detail below.

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully hereinafter with reference to the accompanyingdrawings. This disclosure can, however, be embodied in many differentforms and should not be construed as limited to any specific structureor function presented throughout this disclosure. Rather, these aspectsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the disclosure to those skilled in theart. Based on the teachings herein one skilled in the art shouldappreciate that the scope of the disclosure is intended to cover anyaspect of the novel systems, apparatuses, and methods disclosed herein,whether implemented independently of, or combined with, any other aspectof the invention. For example, an apparatus can be implemented or amethod can be practiced using any number of the aspects set forthherein. In addition, the scope of the invention is intended to coversuch an apparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to or otherthan the various aspects of the invention set forth herein. It should beunderstood that any aspect disclosed herein can be embodied by one ormore elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

Popular wireless network technologies can include various types ofwireless local area networks (WLANs). A WLAN can be used to interconnectnearby devices together, employing widely used networking protocols. Thevarious aspects described herein can apply to any communicationstandard, such as a wireless protocol.

In some aspects, wireless signals can be transmitted according to an802.11 protocol. In some implementations, a WLAN includes variousdevices which are the components that access the wireless network. Forexample, there can be two types of devices: access points (APs) andclients (also referred to as stations, or STAs). In general, an AP canserve as a hub or base station for the WLAN and an STA serves as a userof the WLAN. For example, an STA can be a laptop computer, a personaldigital assistant (PDA), a mobile phone, etc. In an example, an STAconnects to an AP via a WiFi compliant wireless link to obtain generalconnectivity to the Internet or to other wide area networks. In someimplementations an STA can also be used as an AP.

An access point (AP) can also include, be implemented as, or known as abase station, wireless access point, access node or similar terminology.

A station “STA” can also include, be implemented as, or known as anaccess terminal (AT), a subscriber station, a subscriber unit, a mobilestation, a remote station, a remote terminal, a user terminal, a useragent, a user device, user equipment, or some other terminology.Accordingly, one or more aspects taught herein can be incorporated intoa phone (e.g., a cellular phone or smartphone), a computer (e.g., alaptop), a portable communication device, a headset, a portablecomputing device (e.g., a personal data assistant), an entertainmentdevice (e.g., a music or video device, or a satellite radio), a gamingdevice or system, a global positioning system device, or any othersuitable device that is configured for network communication via awireless medium.

As discussed above, certain of the devices described herein canimplement an 802.11 standard, for example. Such devices, whether used asan STA or AP or other device, can be used for smart metering or in asmart grid network. Such devices can provide sensor applications or beused in home automation. The devices can instead or in addition be usedin a healthcare context, for example for personal healthcare. They canalso be used for surveillance, to enable extended-range Internetconnectivity (e.g., for use with hotspots), or to implementmachine-to-machine communications.

FIG. 1 illustrates an example of a wireless communication system 100 inwhich aspects of the present disclosure can be employed. The wirelesscommunication system 100 can operate pursuant to a wireless standard,for example at least one of the 802.11ah, 802.11ac, 802.11n, 802.11g and802.11b standards. The wireless communication system 100 can operatepursuant to a high-efficiency wireless standard, for example the802.11ax standard. The wireless communication system 100 can include anAP 104, which communicates with STAs 106A-106D (which can be genericallyreferred to herein as STA(s) 106).

A variety of processes and methods can be used for transmissions in thewireless communication system 100 between the AP 104 and the STAs106A-106D. For example, signals can be sent and received between the AP104 and the STAs 106A-106D in accordance with OFDM/OFDMA techniques. Ifthis is the case, the wireless communication system 100 can be referredto as an OFDM/OFDMA system. Alternatively, signals can be sent andreceived between the AP 104 and the STAs 106A-106D in accordance withcode division multiple access (CDMA) techniques. If this is the case,the wireless communication system 100 can be referred to as a CDMAsystem.

A communication link that facilitates transmission from the AP 104 toone or more of the STAs 106A-106D can be referred to as a downlink (DL)108, and a communication link that facilitates transmission from one ormore of the STAs 106A-106D to the AP 104 can be referred to as an uplink(UL) 110. Alternatively, a downlink 108 can be referred to as a forwardlink or a forward channel, and an uplink 110 can be referred to as areverse link or a reverse channel.

The AP 104 can act as a base station and provide wireless communicationcoverage in a basic service area (BSA) 102. The AP 104 along with theSTAs 106A-106D associated with the AP 104 and that use the AP 104 forcommunication can be referred to as a basic service set (BSS). It can benoted that the wireless communication system 100 may not have a centralAP 104, but rather can function as a peer-to-peer network between theSTAs 106A-106D. Accordingly, the functions of the AP 104 describedherein can alternatively be performed by one or more of the STAs106A-106D.

In some aspects, a STA 106 can be required to associate with the AP 104in order to send communications to and/or receive communications fromthe AP 104. In one aspect, information for associating is included in abroadcast by the AP 104. To receive such a broadcast, the STA 106 can,for example, perform a broad coverage search over a coverage region. Asearch can also be performed by the STA 106 by sweeping a coverageregion in a lighthouse fashion, for example. After receiving theinformation for associating, the STA 106 can transmit a referencesignal, such as an association probe or request, to the AP 104. In someaspects, the AP 104 can use backhaul services, for example, tocommunicate with a larger network, such as the Internet or a publicswitched telephone network (PSTN).

In an embodiment, the AP 104 includes an AP high efficiency wirelesscontroller (HEW) 154. The AP HEW 154 can perform some or all of theoperations described herein to enable communications between the AP 104and the STAs 106A-106D using the 802.11 protocol. The functionality ofthe AP HEW 154 is described in greater detail below with respect toFIGS. 4-20.

Alternatively or in addition, the STAs 106A-106D can include a STA HEW156. The STA HEW 156 can perform some or all of the operations describedherein to enable communications between the STAs 106A-106D and the AP104 using the 802.11 protocol. The functionality of the STA HEW 156 isdescribed in greater detail below with respect to FIGS. 2-11.

FIG. 2 illustrates various components that can be utilized in a wirelessdevice 202 that can be employed within the wireless communication system100 of FIG. 1. The wireless device 202 is an example of a device thatcan be configured to implement the various methods described herein. Forexample, the wireless device 202 can include the AP 104 or one of theSTAs 106A-106D.

The wireless device 202 can include a processor 204 which controlsoperation of the wireless device 202. The processor 204 can also bereferred to as a central processing unit (CPU) or hardware processor.Memory 206, which can include both read-only memory (ROM) and randomaccess memory (RAM), provides instructions and data to the processor204. A portion of the memory 206 can also include non-volatile randomaccess memory (NVRAM). The processor 204 typically performs logical andarithmetic operations based on program instructions stored within thememory 206. The instructions in the memory 206 can be executable toimplement the methods described herein.

The processor 204 can include or be a component of a processing systemimplemented with one or more processors. The one or more processors canbe implemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that canperform calculations or other manipulations of information. Theprocessor 204 or the processor 204 and the memory 206 can correspond tothe packet generator 124 of FIG. 1, which can be utilized to generate apacket including a value in a packet type field and to allocate aplurality of bits of the packet to each of a plurality of subsequentfields based at least in part on the value in the packet type field, ascan be described in more detail below.

The processing system can also include non-transitory machine-readablemedia for storing software. Software shall be construed broadly to meanany type of instructions, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Instructions can include code (e.g., in source code format, binary codeformat, executable code format, or any other suitable format of code).The instructions, when executed by the one or more processors, cause theprocessing system to perform the various functions described herein.

The wireless device 202 can also include a housing 208 that can includea transmitter 210 and a receiver 212 to allow transmission and receptionof data between the wireless device 202 and a remote location. Thetransmitter 210 and receiver 212 can be combined into a transceiver 214.An antenna 216 can be attached to the housing 208 and electricallycoupled to the transceiver 214. The wireless device 202 can also include(not shown) multiple transmitters, multiple receivers, multipletransceivers, and/or multiple antennas, which can be utilized duringmultiple-input multiple-output (MIMO) communications, for example.

The wireless device 202 can also include a signal detector 218 that canbe used in an effort to detect and quantify the level of signalsreceived by the transceiver 214. The signal detector 218 can detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 202 can alsoinclude a digital signal processor (DSP) 220 for use in processingsignals. The DSP 220 can be configured to generate a data unit fortransmission. In some aspects, the data unit can include a physicallayer data unit (PPDU). In some aspects, the PPDU is referred to as apacket.

The wireless device 202 can further include a user interface 222 in someaspects. The user interface 222 can include a keypad, a microphone, aspeaker, and/or a display. The user interface 222 can include anyelement or component that conveys information to a user of the wirelessdevice 202 and/or receives input from the user.

The various components of the wireless device 202 can be coupledtogether by a bus system 226. The bus system 226 can include a data bus,for example, as well as a power bus, a control signal bus, and a statussignal bus in addition to the data bus. Those of skill in the art canappreciate the components of the wireless device 202 can be coupledtogether or accept or provide inputs to each other using some othermechanism.

Although a number of separate components are illustrated in FIG. 2,those of skill in the art can recognize that one or more of thecomponents can be combined or commonly implemented. For example, theprocessor 204 can be used to implement not only the functionalitydescribed above with respect to the processor 204, but also to implementthe functionality described above with respect to the signal detector218 and/or the DSP 220. Further, each of the components illustrated inFIG. 2 can be implemented using a plurality of separate elements.

As discussed above, the wireless device 202 can include the AP 104 orone of the STAs 106A-106D, and can be used to transmit and/or receivecommunications. The communications exchanged between devices in awireless network can include data units which can include packets orframes. In some aspects, the data units can include data frames, controlframes, and/or management frames. Data frames can be used fortransmitting data from an AP and/or a STA to other APs and/or STAs.Control frames can be used together with data frames for performingvarious operations and for reliably delivering data (e.g., acknowledgingreceipt of data, polling of APs, area-clearing operations, channelacquisition, carrier-sensing maintenance functions, etc.). Managementframes can be used for various supervisory functions (e.g., for joiningand departing from wireless networks, etc.).

FIG. 3 illustrates a channel allocation for channels available for802.11 systems. Various IEEE 802.11 systems support a number ofdifferent sizes of channels, such as 5, 10, 20, 40, 80, and 160 MHzchannels. For example, and 802.11ac device can support 20, 40, and 80MHz channel bandwidth reception and transmission. A larger channel caninclude two adjacent smaller channels. For example, an 80 MHz channelcan include two adjacent 40 MHz channels. In the currently implementedIEEE 802.11 systems, a 20 MHz channel contains 64 subcarriers, separatedfrom each other by 312.5 kHz. Of these subcarriers, a smaller number canbe used for carrying data. For example, a 20 MHz channel can containtransmitting subcarriers numbered −1 to −28 and 1 to 28, or 56subcarriers. Some of these carriers can also be used to transmit pilotsignals.

FIGS. 4 and 5 illustrate data packet formats for several currentlyexisting IEEE 802.11 standards. Turning first to FIG. 4, a packet formatfor IEEE 802.11a, 11b, and 11g is illustrated. This frame includes ashort training field 422, a long training field 424, and a signal field426. The training fields do not transmit data, but they allowsynchronization between the AP and the receiving STAs for decoding thedata in the data field 428.

The signal field 426 delivers information from the AP to the STAs aboutthe nature of the packet being delivered. In IEEE 802.11a/b/g devices,this signal field has a length of 24 bits, and is transmitted as asingle OFDM symbol at a 6 Mb/s rate using binary phase shift keying(BPSK) modulation and a code rate of ½. The information in the signal(SIG) field 426 includes 4 bits describing the modulation scheme of thedata in the packet (e.g., BPSK, 16QAM, 64QAM, etc.), and 12 bits for thepacket length. This information is used by a STA to decode the data inthe packet when the packet is intended for the STA. When a packet is notintended for a particular STA, the STA can defer any communicationattempts during the time period defined in the length field of the SIGsymbol 426, and can, to save power, enter a sleep mode during the packetperiod of up to about 5.5 msec.

As features have been added to IEEE 802.11, changes to the format of theSIG fields in data packets were developed to provide additionalinformation to STAs. FIG. 5 shows the packet structure for the IEEE802.11n packet. The 11n addition to the IEEE.802.11 standard added MIMOfunctionality to IEEE.802.11 compatible devices. To provide backwardcompatibility for systems containing both IEEE 802.11a/b/g devices andIEEE 802.11n devices, the data packet for IEEE 802.11n systems alsoincludes the STF, LTF, and SIG fields of these earlier systems, noted asL-STF 422, L-LTF 424, and L-SIG 426 with a prefix L to denote that theyare “legacy” fields. To provide the needed information to STAs in anIEEE 802.11n environment, two additional signal symbols 440 and 442 wereadded to the IEEE 802.11n data packet. In contrast with the SIG fieldand L-SIG field 426, however, these signal fields used rotated BPSKmodulation (also referred to as QBPSK modulation). When a legacy deviceconfigured to operate with IEEE 802.11a/b/g receives such a packet, itcan receive and decode the L-SIG field 426 as a normal 11/b/g packet.However, as the device continued decoding additional bits, they may notbe decoded successfully because the format of the data packet after theL-SIG field 426 is different from the format of an 11/b/g packet, andthe CRC check performed by the device during this process can fail. Thiscauses these legacy devices to stop processing the packet, but stilldefer any further operations until a time period has passed defined bythe length field in the initially decoded L-SIG. In contrast, newdevices compatible with IEEE 802.11n would sense the rotated modulationin the HT-SIG fields, and process the packet as an 802.11n packet.Furthermore, an 11n device can tell that a packet is intended for an11/b/g device because if it senses any modulation other than QBPSK inthe symbol following the L-SIG 426, it can ignore it as an 11/b/gpacket. After the HT-SIG1 and SIG2 symbols, additional training fieldssuitable for MIMO communication are provided, followed by the data 428.

FIG. 6 illustrates a frame format for the currently existing IEEE802.11ac standard, which added multi-user MIMO functionality to the IEEE802.11 family. Similar to IEEE 802.11n, an 802.11ac frame contains thesame legacy short training field (L-STF) 422 and long training field(L-LTF) 424. An 802.11ac frame also contains a legacy signal field L-SIG426 as described above.

Next, an 802.11ac frame includes a Very High Throughput Signal(VHT-SIG-A1 450 and A2 452) field two symbols in length. This signalfield provides additional configuration information related to 11acfeatures that are not present in 11/b/g and 11n devices. The first OFDMsymbol 450 of the VHT-SIG-A can be modulated using BPSK, so that any802.11n device listening to the packet can believe the packet to be an802.11a packet, and can defer to the packet for the duration of thepacket length as defined in the length field of the L-SIG 426. Devicesconfigured according to 11/g can be expecting a service field and mediaaccess control (MAC) header following the L-SIG 426 field. When theyattempt to decode this, a CRC failure can occur in a manner similar tothe procedure when an 11n packet is received by an 11a/b/g device, andthe 11/b/g devices can also defer for the period defined in the L-SIGfield 426. The second symbol 452 of the VHT-SIG-A is modulated with a90-degree rotated BPSK. This rotated second symbol allows an 802.11acdevice to identify the packet as an 802.11ac packet. The VHT-SIGA1 450and A2 452 fields contain information on a bandwidth mode, modulationand coding scheme (MCS) for the single user case, number of space timestreams (NSTS), and other information. The VHT-SIGA1 450 and A2 452 canalso contain a number of reserved bits that are set to “1.” The legacyfields and the VHT-SIGA1 and A2 fields can be duplicated over each 20MHz of the available bandwidth. Although duplication may be constructedto mean making or being an exact copy, certain differences may existwhen fields, etc. are duplicated as described herein.

After the VHT-SIG-A, an 802.11ac packet can contain a VHT-STF, which isconfigured to improve automatic gain control estimation in amultiple-input and multiple-output (MIMO) transmission. The next 1 to 8fields of an 802.11ac packet can be VHT-LTFs. These can be used forestimating the MIMO channel and then equalizing the received signal. Thenumber of VHT-LTFs sent can be greater than or equal to the number ofspatial streams per user. Finally, the last field in the preamble beforethe data field is the VHT-SIG-B 454. This field is BPSK modulated, andprovides information on the length of the useful data in the packet and,in the case of a multiple user (MU) MIMO packet, provides the MCS. In asingle user (SU) case, this MCS information is instead contained in theVHT-SIGA2. Following the VHT-SIG-B, the data symbols are transmitted

Although 802.11ac introduced a variety of new features to the 802.11family, and included a data packet with preamble design that wasbackward compatible with 11/g/n devices and also provided informationnecessary for implementing the new features of 11ac, configurationinformation for OFDMA tone allocation for multiple access is notprovided by the 11ac data packet design. New preamble configurations aredesired to implement such features in any future version of IEEE 802.11or any other wireless network protocol using OFDM subcarriers.

FIG. 7 illustrates an exemplary structure of a physical-layer packetwhich can be used to enable backward-compatible multiple access wirelesscommunications. In this example physical-layer packet, a legacy preambleincluding the L-STF 422, L-LTF 426, and L-SIG 426 are included. Invarious embodiments, each of the L-STF 422, L-LTF 426, and L-SIG 426 canbe transmitted using 20 MHz, and multiple copies can be transmitted foreach 20 MHz of spectrum that the AP 104 (FIG. 1) uses. A person havingordinary skill in the art can appreciate that the illustratedphysical-layer packet can include additional fields, fields can berearranged, removed, and/or resized, and the contents of the fieldsvaried. This packet also contains an HE-SIG0 symbol 455, and one or moreHE-SIG1A symbols 457 (which can be variable in length), and an optionalHE-SIG1B symbol 459 (which can be analogous to the VHT-SIG1B field 454of FIG. 4). In various embodiments, the structure of these fields can bebackward compatible with IEEE 802.11a/b/g/n/ac devices, and can alsosignal OFDMA HE devices that the packet is an HE packet. To be backwardcompatible with IEEE 802.11a/b/g/n/ac devices, appropriate modulationcan be used on each of these symbols. In some implementations, theHE-SIG0 field 455 can be modulated with BPSK modulation. This can havethe same effect on 802.11a/b/g/n devices as is currently the case with802.11ac packets that also have their first SIG symbol BPSK modulated.For these devices, it does not matter what the modulation is on thesubsequent HE-SIG symbols 457. In various embodiments, the HE-SIG0 field455 can be modulated and repeated across multiple channels.

In various embodiments, the HE-SIG1A field 457 can be BPSK or QBPSKmodulated. If BPSK modulated, an 11ac device can assume the packet is an802.11a/b/g packet, and can stop processing the packet, and can deferfor the time defined by the length field of L-SIG 426. If QBPSKmodulated, an 802.11ac device can produce a CRC error during preambleprocessing, and can also stop processing the packet, and can defer forthe time defined by the length field of L-SIG. To signal HE devices thatthis is an HE packet, at least the first symbol of HE-SIG1A 457 can beQBPSK modulated.

The information necessary to establish an OFDMA multiple accesscommunication can be placed in the HE-SIG fields 455, 457, and 459 in avariety of positions. In various embodiments, the HE-SIG0 455 caninclude one or more of: a duration indication, a bandwidth indication(which can be, for example, 2 bits), a BSS color ID (which can be, forexample, 3 bits), an UL/DL indication (which can be, for example, a1-bit flag), a cyclic redundancy check (CRC) (which can be, for example,4 bits), and a clear channel assessment (CCA) indication (which can be,for example, 2 bits).

In various embodiments, the HE-SIG1 field 457 can include a toneallocation information for OFDMA operation. The example of FIG. 7 canallow four different users to be each assigned a specific sub-band oftones and a specific number of MIMO space time streams. In variousembodiments, 12 bits of space time stream information allows three bitsfor each of four users such that 1-8 streams can be assigned to eachone. 16 bits of modulation type data allows four bits for each of fourusers, allowing assignment of any one of 16 different modulation schemes(16QAM, 64QAM, etc.) to each of four users. 12 bits of tone allocationdata allows specific sub-bands to be assigned to each of four users.

One example SIG field scheme for sub-band (also referred to herein assub-channel) allocation includes a 6-bit Group ID field as well as 10bits of information to allocate sub-band tones to each of four users.The bandwidth used to deliver a packet can be allocated to STAs inmultiples of some number of MHz. For example, the bandwidth can beallocated to STAs in multiples of B MHz. The value of B can be a valuesuch as 1, 2, 5, 10, 15, or 20 MHz. The values of B can be provided by atwo bit allocation granularity field. For example, the HE-SIG1A 457 cancontain one two-bit field, which allows for four possible values of B.For example, the values of B can be 5, 10, 15, or 20 MHz, correspondingto values of 0-3 in the allocation granularity field. In some aspects, afield of k bits can be used to signal the value of B, defining a numberfrom 0 to N, where 0 represents the least flexible option (largestgranularity), and a high value of N represents the most flexible option(smallest granularity). Each B MHz portion can be referred to as asub-band.

The HE-SIG1A 457 can further use 2 bits per user to indicate the numberof sub-bands allocated to each STA. This can allow 0-3 sub-bands to beallocated to each user. The group-id (G_ID) can be used in order toidentify the STAs, which can receive data in an OFDMA packet. This 6-bitG_ID can identify up to four STAs, in a particular order, in thisexample.

The training fields and data which are sent after the HE-SIG symbols canbe delivered by the AP according to the allocated tones to each STA.This information can potentially be beamformed. Beamforming thisinformation can have certain advantages, such as allowing for moreaccurate decoding and/or providing more range than non-beamformedtransmissions.

Depending on the space time streams assigned to each user, differentusers can use a different number of HE-LTFs 465. Each STA can use anumber of HE-LTFs 465 that allows channel estimation for each spatialstream associated with that STA, which can be generally equal to or morethan the number of spatial streams. LTFs can also be used for frequencyoffset estimation and time synchronization. Because different STAs canreceive a different number of HE-LTFs, symbols can be transmitted fromthe AP 104 (FIG. 1) that contain HE-LTF information on some tones anddata on other tones.

In some aspects, sending both HE-LTF information and data on the sameOFDM symbol can be problematic. For example, this can increase thepeak-to-average power ratio (PAPR) to too high a level. Thus, it can bebeneficial to instead to transmit HE-LTFs 465 on all tones of thetransmitted symbols until each STA has received at least the requirednumber of HE-LTFs 465. For example, each STA can need to receive oneHE-LTF 465 per spatial stream associated with the STA. Thus, the AP canbe configured to transmit a number of HE-LTFs 465 to each STA equal tothe largest number of spatial streams assigned to any STA. For example,if three STAs are assigned a single spatial stream, but the fourth STAis assigned three spatial streams, in this aspect, the AP can beconfigured to transmit four symbols of HE-LTF information to each of thefour STAs before transmitting symbols containing payload data.

It is not necessary that the tones assigned to any given STA beadjacent. For example, in some implementations, the sub-bands of thedifferent receiving STAs can be interleaved. For example, if each ofuser-1 and user-2 receive three sub-bands, while user-4 receives twosub-bands, these sub-bands can be interleaved across the entire APbandwidth. For example, these sub-bands can be interleaved in an ordersuch as 1,2,4,1,2,4,1,2. In some aspects, other methods of interleavingthe sub-bands can also be used. In some aspects, interleaving thesub-bands can reduce the negative effects of interferences or the effectof poor reception from a particular device on a particular sub-band. Insome aspects, the AP can transmit to STAs on the sub-bands that the STAprefers. For example, certain STAs can have better reception in somesub-bands than in others. The AP can thus transmit to the STAs based atleast in part on which sub-bands the STA can have better reception. Insome aspects, the sub-bands can also not be interleaved. For example,the sub-bands can instead be transmitted as 1,1,1,2,2,2,4,4. In someaspects, it can be pre-defined whether or not the sub-bands areinterleaved.

In the example of FIG. 7, HE-SIG0 455 symbol modulation can be used tosignal HE devices that the packet is an HE packet. Other methods ofsignaling HE devices that the packet is an HE packet can also be used.In the example of FIG. 7, the L-SIG 426 can contain information thatinstructs HE devices that an HE preamble can follow the legacy preamble.For example, the L-SIG 426 can contain a low-energy, 1-bit code on theQ-rail which indicates the presence of a subsequent HE preamble to HEdevices sensitive to the Q signal during the L-SIG 426. A very lowamplitude Q signal can be used because the single bit signal can bespread across all the tones used by the AP to transmit the packet. Thiscode can be used by high efficiency devices to detect the presence of anHE-preamble/packet. The L-SIG 426 detection sensitivity of legacydevices need not be significantly impacted by this low-energy code onthe Q-rail. Thus, these devices can be able to read the L-SIG 426, andnot notice the presence of the code, while HE devices can be able todetect the presence of the code. In this implementation, all of theHE-SIG fields can be BPSK modulated if desired, and any of thetechniques described herein related to legacy compatibility can be usedin conjunction with this L-SIG signaling.

In various embodiments, any HE-SIG field 455-459 can contain bitsdefining user-specific modulation type for each multiplexed user. Forexample, the optional HE-SIG1B 459 field can contain bits defininguser-specific modulation type for each multiplexed user.

In some aspects, wireless signals can be transmitted in a low-rate (LR)mode, for example according the 802.11ax protocol. Particularly, in someembodiments, the AP 104 can have a greater transmit power capabilitycompared to the STAs 106. In some embodiments, for example, the STAs 106can transmit at several dB lower than the AP 104. Thus, DLcommunications from the AP 104 to the STAs 106 can have a higher rangethan UL communications from the STAs 106 to the AP 104. In order toclose the link budget, the LR mode can be used. In some embodiments, theLR mode can be used in both DL and UL communications. In otherembodiments, the LR mode is only used for UL communications.

In some embodiments, the HEW STAs 106 can communicate using a symbolduration four times that of a legacy STA. Accordingly, each symbol whichis transmitted may be four times as long in duration. When using alonger symbol duration, each of the individual tones may only requireone-quarter as much bandwidth to be transmitted. For example, in variousembodiments, a 1× symbol duration can be 4 ms and a 4× symbol durationcan be 16 ms. Thus, in various embodiments, 1× symbols can be referredto herein as legacy symbols and 4× symbols can be referred to as HEWsymbols. In other embodiments, different durations are possible.

FIG. 8 illustrates an exemplary structure of an uplink or downlinkphysical-layer packet 800 which can be used to enable wirelesscommunications. In the illustrated embodiment, the physical-layer packet800 includes a legacy preamble 805 including the L-STF 422, L-LTF 426,and L-SIG 426, an HE preamble 810 including an HE-SIG0 815, an HE-STF820, an HE-LTF 825, and an HE-SIG1 830, and a payload 835. A personhaving ordinary skill in the art will appreciate that the illustratedphysical-layer packet 800 can include additional fields, fields can berearranged, removed, and/or resized, and the contents of the fieldsvaried.

Certain aspects of the present disclosure support mixing MU-MIMO andOFDMA techniques in the frequency domain in a same PPDU. In someembodiments, a first portion of the PPDU bandwidth can be transmitted asa one of at least a MU-MIMO transmission and an OFDMA transmission. Asecond portion of the PPDU bandwidth can be transmitted as one of atleast a MU-MIMO transmission and an OFDMA transmission. In variousembodiments, each portion can be referred to as a “zone.” Thus, invarious embodiments, the first and second portions can include anycombination such as MU-MIMO/OFDMA, MU-MIMO/MU-MIMO, OFDMA/OFDMA, andOFDMA/OFDMA.

In some embodiments, the PPDU bandwidth can include more than twoportions or zones. In some embodiments, the PPDU bandwidth can belimited to a single zone or a maximum of two zones. For example, FIG. 8shows a two-zone configuration including a MU-MIMO zone 840 and an OFDMAzone 845. In these embodiments, MU-MIMO or OFDMA transmissions can besent simultaneously from an AP to multiple STAs and can createefficiencies in wireless communication. Although the two zones 840 and845 are shown in FIG. 8, a person having ordinary skill in the art willappreciate that other combinations are possible within the scope of thisdisclosure.

In various embodiments, each of the L-STF 422, L-LTF 426, and L-SIG 426can be transmitted using 20 MHz, and multiple copies can be transmittedfor each 20 MHz of spectrum that the AP 104 (FIG. 1) uses. Anycombination of the HE-SIG0 815, the HE-STF 820, the HE-LTF 825, theHE-SIG1 830, and the payload 835 can be transmitted for each of one ormore OFDMA users. In the illustrated embodiment, two users 1-2 share theillustrated 40 MHz bandwidth, and a portion of the 40 MHz bandwidth isnot assigned to any users. An one embodiment, user 1 can correspond tothe STA 106A (FIG. 1) and user 2 can correspond to the STA 106B (FIG.1).

Although the packet 800 is referred to herein as a single packet, invarious embodiments the transmissions associated with each zone, oralternatively with each user, can be referred to as a separate packet.Although the packet 800 can be used for UL and DL transmissions, ULtransmissions will be discussed in greater detail herein. A personhaving ordinary skill in the art will appreciate that discussion relatedto UL transmissions from the STAs 106 to the AP 104 can also be appliedto DL transmissions from the AP 104 to the STAs 106.

In the illustrated embodiment, the packet 800 uses a 1× symbol duration.In other embodiments, the 4× symbol duration can be used for at least aportion of the packet 800 such as, for example, any portion of the HEpreamble 810 and/or the payload 835. In the illustrated embodiment, theL-STF 422 is 8 μs (i.e., two 1× symbols) long, the L-LTF 424 is 8 μs(i.e., two 1× symbols) long, the L-SIG 426 is 4 μs (i.e., one 1× symbol)long, the HE-SIG0 815 is from 4 μs (i.e., one 1× symbol) long to 8 μs(i.e., two 1× symbols) long, the HE-STF 820 is from 4 μs (i.e., one 1×symbol) long to 8 μs (i.e., two 1× symbols) long, and the HE-LTF 825 isa variable length, which can be dependent on the number of spatialstreams (NSS) used for transmission of the payload 835.

Duplication of Legacy Preamble

In one embodiment, the packet 800 is an UL packet. In one UL embodiment,STAs can be configured to transmit the legacy preamble 805 an entirechannel to which it is assigned. For example, the STA user 1 cantransmit the legacy preamble 805 over the upper 20 MHz channel shown inFIG. 8, even in embodiments where the STA user 1 is not assigned theentire 20 MHz channel. Similarly, the STA user 2 can transmit the legacypreamble 805 over the lower 20 MHz channel shown in FIG. 8, even inembodiments where the STA user 2 is not assigned the entire 20 MHzchannel. Such embodiments can advantageously simplify transmission bydecreasing the bandwidth of transmission.

In one embodiment, the STAs can be configured to transmit the legacypreamble 805 over an entire zone to which it is assigned. For example,the STA user 1 can transmit the legacy preamble 805 over the entireMU-MIMO zone 840. Similarly, the STA user 2 can transmit the legacypreamble 805 over the entire OFDMA zone 845, even though it is notassigned the entire zone.

In one embodiment, STAs can be configured to transmit the legacypreamble 805 over an entire bandwidth available, including bandwidth towhich the STA user 1 is not assigned. For example, the STA user 1 cantransmit the legacy preamble 805 over the entire illustrated 40 MHzbandwidth, including both the MU-MIMO zone 840 and the OFDMA zone 845.Similarly, the STA user 2 can transmit the legacy preamble 805 over theentire illustrated 40 MHz bandwidth, including both the MU-MIMO zone 840and the OFDMA zone 845.

In one embodiment, STAs can be configured to transmit the legacypreamble 805 over an entire channel to which it is assigned, plus aprimary channel when the STA is not assigned a primary channel. Forexample, assume that the upper 20 MHz channel illustrated in FIG. 8 is aprimary channel. The STA user 1 can transmit the legacy preamble 805over upper 20 MHz channel shown in FIG. 8, even in embodiments where theSTA user 1 is not assigned the entire 20 MHz channel. On the other hand,because the STA user 2 is not assigned to the primary channel, the STAuser 2 can transmit the legacy preamble 805 over the entire illustrated40 MHz bandwidth, including both the MU-MIMO zone 840 and the OFDMA zone845. Such embodiments can advantageously ensure that the legacy preamble805 is transmitted over the entire available bandwidth, even when no STAis assigned to the primary channel.

In an embodiment, transmission of data “over” a certain channel orbandwidth includes duplicating the data in a plurality of sub-channelsthat compose the channel or bandwidth. For example, the STA user 1 canseparately modulate the legacy preamble 805 in both the upper and lower20 MHz sub-bands of the illustrated 40 MHz bandwidth. In anotherembodiment, transmission of data “over” a certain channel or bandwidthincludes combined modulation of the data with respect to the channel orbandwidth. For example, the STA user 2 can treat the entire illustrated40 MHz bandwidth as a single OFDMA channel.

L-SIG Length Field

In some embodiments, different users can have different frame lengths.For example, the STA user 1 can have more data 835 than the STA user 2,or the HE-LTF 825 for the STA user 1 can be longer than the HE-LTF 825for the STA user 2 (for example, where user 1 is assigned more spatialstreams than user 2).

In one embodiment, the L-SIG 426 for the STA user 1 can be differentfrom the L-SIG 426 for the STA user 2, where the frame length for user 1is different from the frame length for user 2. For example, the L-SIGs426 can include a length field indicating a different frame length forthe STA user 1 and the STA user 2.

In one embodiment, the L-SIG 426 can be the same for each zone, evenwhere the frame length is different for users within a zone. Forexample, the L-SIG 426 for each zone can include a length field set tothe maximum of frame lengths for each user in the zone. The SIG 426 canbe different between zones where the frame length is different betweenzones. For example, the L-SIGs 426 can include a length field indicatinga different frame length for the MU-MIMO zone 840 than for the OFDMAzone 845.

In one embodiment, the L-SIGs 426 can be the same across all users andzones, even where the frame length is different between users. Forexample, the L-SIG 426 can include a length field set to the maximum offrame lengths for each user. Such embodiments can advantageouslyincrease transmission power for the legacy preamble 805. In someembodiments, one or more fields are padded to the value of the lengthfield. For example, the payload 835 for the STA user 1 can smaller thanthe payload 835 for the STA user 2, and can be padded out match thepayload 835 for the STA user 2.

HE-SIG0 Field

In one embodiment, the packet 800 can omit the HE-SIG0 fields 915,thereby reducing overhead. In another embodiment, the packet 800includes the HE-SIG0 fields 815. Including the HE-SIG0 fields 820 canadvantageously convey additional information (such as, for example, aDL/UL mode, SU/UL mode, MU-OFDMA mode, BSS color ID, etc.) for exampleto bystander devices to which the packet is not addressed. FIGS. 9A-9Eshow various exemplary packet configurations including the HE-SIG0 815of FIG. 8.

In various embodiments, the HE-SIG0 fields 815 can include a full orpartial BSS color ID. In some embodiments, the partial BSSID can includea hash of the AP 104 BSSID MAC address, or another number uniquely orpseudo-uniquely associated with the AP 104. The partial BSSID can beused, for example, for controlling reuse in dense networks. Accordingly,STAs associated with the partial BSSID can defer at the packet detection(PD) level to avoid intra-BSS hidden nodes. Overlapping basic serviceset (OBSS) STAs can defer at the energy detection (ED) level, therebyimproving reuse. Moreover, the partial BSSID can enable interferencesource identification, which in some embodiments can enable TXOP reuse.Additionally, STAs can enter power-save modes based on the partialBSSID, in some embodiments in combination with a receiver association ID(AID) and/or a UL/DL indication.

In various embodiments, the HE-SIG0 fields 815 can include a full orpartial receiver AID. For example, the partial receiver AID can includea truncated or hashed version of the receiver AID. STAs 106 can use thefull or partial receiver AID in order to enter a power save mode whendetermining that a packet is not addressed to the STA 106. Moreover, theSTAs 106 can use the full or partial receiver AID for TXOP reuse in someembodiments.

In various embodiments, the HE-SIG0 fields 815 can include a full orpartial transmitter AID. For example, the partial transmitter AID caninclude a truncated or hashed version of transmitter receiver AID. STAs106 can use the full or partial transmitter AID in order to obtaininterference source identification. Moreover, the STAs 106 can use thefull or partial transmitter AID for TXOP reuse in some embodiments.

In various embodiments, the HE-SIG0 fields 815 can include a UL/DLindication. In some embodiments, the UL/DL indication can be implicit inan AID (transmitter or receiver) indication on the HE-SIG0 fields 815.For example, when the full or partial transmitter AID is included in theHE-SIG0 fields 815, UL can be indicated. When the full or partialreceiver AID is included in the HE-SIG0 fields 815, DL can be indicated(or vice versa in some embodiments). STAs 106 can use the UL/DLindication in order to enter a power save mode when determining that apacket is not addressed to the STA 106 (or expected from the STA 106).Moreover, the STAs 106 can use the UL/DL indication for interferencesource identification in UL/DL scheduling.

In various embodiments, the HE-SIG0 fields 815 can include an immediateresponse presence/duration indication. In some embodiments, theimmediate response presence/duration indication can indicate a deferraltime such as, for example, an extended interframe space (EIFS) or aresponse indication deferral (RID). For example, the immediate responsepresence/duration indication can include a flag indicating whether ornot a response is requested. When a response is indicated, a standarddeferral time can be applied. In other embodiments, the immediateresponse presence/duration indication can be two or more bits long. Insuch embodiments, the immediate response presence/duration indicationcan identify a specific deferral duration, which can map to the bitvalue. In some embodiments, minimum deferral duration can be a shortinterframe space (SIFS), plus a minimum header duration.

In various embodiments, the HE-SIG0 fields 815 can include a transmitpower indication. For example, the transmit power indication can includeone or more bits mapping to one or more transmit powers. A receiving STAcan apply the transmit power indication for transmit opportunity (TXOP)reuse and/or for advanced adaptive CCA rules.

In some embodiments, the HE-SIG0 fields 815 can include synchronizationinformation. For example, the HE-SIG0 fields 815 can indicate a full orpartial time synchronization function (TSF) to establish asynchronization point. In some embodiments, the partial TSF can includea hashed or truncated TSF.

In some embodiments, the HE-SIG0 fields 815 can include a TXOP bandwidth(BW) and/or primary channel offset indication. In some embodiments, theSTAs 106 can use the TXOP BW indication for TXOP reuse. For example, athird-party receiver can determine whether or not to transmit in a freesecondary channel by identifying utilized channels in a TXOP based on tthe TXOP BW and/or primary channel offset.

FIG. 9A illustrates an exemplary structure of an uplink physical-layerpacket 900A which can be used to enable wireless communications. In theillustrated embodiment, the physical-layer packet 900A includes theL-STF 422, L-LTF 426, the L-SIG 426, a repeated L-SIG (RL-SIG) 910, theHE-SIG0 815, the HE-STF 820, the HE-LTF 825, the HE-SIG1 830, and thepayload 835. A person having ordinary skill in the art will appreciatethat the illustrated physical-layer packet 800 can include additionalfields, fields can be rearranged, removed, and/or resized, and thecontents of the fields varied.

In the illustrated embodiment, the RL-SIG 910 includes total or partialrepetition of the L-SIG 426. For example, in an embodiment, the RL-SIG910 can include a repetition of even tones of the L-SIG 426. In anembodiment, the RL-SIG 910 can include a repetition of odd tones of theL-SIG 426. In an embodiment, the RL-SIG 910 can include a repetition ofevery X tones of the L-SIG 426, where X is the ratio of symbol durationfor the L-SIG 426 to symbol duration for the RL-SIG 910. In anembodiment, the HE-SIG0 815 is 4 μs, plus a guard interval (GI).

In various embodiments, the STA 106 can encode HE-SIG information in apolarity of repeated symbols. For example, to encode a 1, the STA 106can multiply the repeated bits in the L-SIG 426 by −1, to encode a 0,the STA 106 can multiply the repeated bits in the L-SIG 426 by 1, and soon. In various embodiments, positive and negative repetition polaritiescan represent 0 and 1, respectively. In other embodiments, differentencodings are possible. Note that information bit [0, 1] becomemodulation bit [1, −1] in one embodiment. Changing the polarity of asymbol means multiply it with +−1 instead of [0, 1].

FIG. 9B illustrates another exemplary structure of an uplinkphysical-layer packet 900B which can be used to enable wirelesscommunications. In the illustrated embodiment, the physical-layer packet900B includes the L-STF 422, L-LTF 426, the L-SIG 426, the HE-SIG0 815,a repeated HE-SIG0 (RHE-SIG0) 915, an HE-SIG0B 920, the HE-STF 820, theHE-LTF 825, the HE-SIG1 830, and the payload 835. A person havingordinary skill in the art will appreciate that the illustratedphysical-layer packet 800 can include additional fields, fields can berearranged, removed, and/or resized, and the contents of the fieldsvaried. For example, the HE-SIG0B 920 can be omitted in someembodiments.

In the illustrated embodiment, the RHE-SIG0 915 includes total orpartial repetition of the HE-SIG0 815. For example, in an embodiment,the RHE-SIG0 915 can include a repetition of even tones of the HE-SIG0815. In an embodiment, the RHE-SIG0 915 can include a repetition of oddtones of the HE-SIG0 815. In an embodiment, the RHE-SIG0 915 can includea repetition of every X tones of the HE-SIG0 815, where X is the ratioof symbol duration for the HE-SIG0 815 to symbol duration for theRHE-SIG0 915. In an embodiment, the HE-SIG0B 920 is 4 μs, plus a guardinterval (GI).

In various embodiments, the STA 106 can encode HE-SIG information in apolarity of repeated symbols. For example, to encode a 1, the STA 106can multiply the repeated bits in the HE-SIG0 815 by −1, to encode a 0,the STA 106 can multiply the repeated bits in the HE-SIG0 815 by 1, andso on. In various embodiments, positive and negative repetitionpolarities can represent 0 and 1, respectively. In other embodiments,different encodings are possible. Note that information bit [0, 1]become modulation bit [1, −1] in one embodiment. Changing the polarityof a symbol means multiply it with +−1 instead of [0, 1].

FIG. 9C illustrates another exemplary structure of an uplinkphysical-layer packet 900C which can be used to enable wirelesscommunications. In the illustrated embodiment, the physical-layer packet900C includes the L-STF 422, L-LTF 426, the L-SIG 426, the HE-SIG0 815,the HE-STF 820, the HE-LTF 825, the HE-SIG1 830, and the payload 835. Aperson having ordinary skill in the art will appreciate that theillustrated physical-layer packet 800 can include additional fields,fields can be rearranged, removed, and/or resized, and the contents ofthe fields varied. In the illustrated embodiment, the HE-SIG0 815 is 4μs long.

FIG. 9D illustrates another exemplary structure of an uplinkphysical-layer packet 900D which can be used to enable wirelesscommunications. In the illustrated embodiment, the physical-layer packet900D includes L-STF 422, L-LTF 424, L-SIG 426, RL-SIG 910, HE-SIG0 815,a repeated HE-SIG0 (RHE-SIG0) 915, HE-SIG0B 920, HE-STF 820, HE-LTF 825,and payload 835. A person having ordinary skill in the art willappreciate that the illustrated physical-layer packet 900D can includeadditional fields, fields can be rearranged, removed, and/or resized,and the contents of the fields varied. For example, HE-SIG0B 920 orHE-STF 820 can be different lengths in various embodiments.

In the illustrated embodiment, RHE-SIG0 915 includes a total or partialrepetition of HE-SIG0 815. As described above with respect to FIG. 9B,RHE-SIG0 915 can include a repetition of even or odd tones, or of everyX tones. In various embodiments, RHE-SIG0 915 is 4 μs. The use ofRHE-SIG0 915 may provide for a better protected or a more robust packet900D, but may also provide additional overhead in wirelesscommunications. Whether or not RHE-SIG0 915 is present in the packet900D may depend on a variety of factors. For example, the presence ofRHE-SIG0 915 may depend on at least one of the following: the modulationand coding scheme of HE-SIGB0 920; whether HE-SIGB0 920 comprises a longGI; whether HE-SIGB0 920 comprises a short GI; whether HE-LFT 825 isuncompressed; whether HE-LFT 825 is compressed; the compression factorof HE-LFT 825; whether the payload 835 comprises a CP; and the length ofa CP of the payload 835.

HE-SIGB0 920 may comprise a cyclic prefix (CP) or guard interval (GI).The presence of a CP or GI may provide for a better protected or a morerobust packet 900D, but may also provide additional overhead in wirelesscommunications. HE-SIGB0 920 may vary in length for these reasons, andin some embodiments HE-SIGB0 920 may be five or six symbols in length.In some embodiments, HE-SIGB0 920 comprises a short GI. In otherembodiments, HE-SIGB0 920 comprises a long GI. The modulation and codingscheme (MCS) used with HE-SIGB0 920 may also vary. Which MCS is used maybe based upon the presence or the length of the GI of HE-SIGB0 920. Insome exemplary embodiments, MCS0 is utilized. In other exemplaryembodiments, MCS10 is utilized.

HE-LFT 825 may be compressed or uncompressed. An uncompressed HE-LFT 825may provide for a better protected or a more robust packet 900D, but mayalso provide additional overhead in wireless communications.Accordingly, in some embodiments, HE-LFT 825 is uncompressed. In otherembodiments, HE-LFT 825 is compressed. In some of these embodiments,HE-LFT 825 is compressed by a factor of two. In these embodiment, thecompressed HE-LFT 825 may provide less protection of the HE-LFT 825 orthe packet 900D, and therefore RHE-SIG0 915 may be present in the packet900D.

The payload 835 may comprise a cyclic prefix (CP) or guard interval(GI). A longer CP of the payload 835 may provide for a better protectedor a more robust packet 900D, but may also provide additional overheadin wireless communications. Accordingly, in some embodiments, a longerCP is used. In other embodiments, a shorter CP is used. By way ofexample only, CP may be 0.8 μs, 1.6 μs, or 3.2 μs. In one exemplaryembodiment, packet 900D comprises the RHE-SIG0 915, HE-SIG0B 920utilizes MCS10, and HE-LFT 825 is uncompressed.

FIG. 9E illustrates another exemplary structure of an uplinkphysical-layer packet 900E which can be used to enable wirelesscommunications. In the illustrated embodiment, the physical-layer packet900D includes L-STF 422, L-LTF 424, L-SIG 426, RL-SIG 910, HE-SIG0 815,HE-SIG0B 920, HE-STF 820, HE-LTF 825, and payload 835. A person havingordinary skill in the art will appreciate that the illustratedphysical-layer packet 900D can include additional fields, fields can berearranged, removed, and/or resized, and the contents of the fieldsvaried. For example, HE-SIG0B 920 or HE-STF 820 can be different lengthsin various embodiments.

HE-STF Field

Referring back to FIG. 8, in one embodiment, the packet 800 can omit theHE-STF fields 820, thereby reducing overhead. In another embodiment, thepacket 800 includes the HE-STF fields 820. Including the HE-STF fields820 can advantageously convey additional information (such as, forexample, automatic gain control).

HE-LTF Alignment

As discussed above, in some embodiments, the HE-LTF fields 825 can varyin length between users, for example due to different number of spatialstreams. In the illustrated embodiment of FIG. 8, the HE-LTF fields 825are the same size. In various embodiments, the HE-LTF fields 825 can bedifferent sizes.

In one embodiment, the HE-LTF fields 825 can be set to the same size bypadding to the longest of the HE-LTF fields 825 across the entireavailable bandwidth. For example, assuming the HE-LTF 825 for the STAuser 2 is shorter than the HE-LTF 825 for the STA user 1, the STA user 2can pad its HE-LTF 825 length to match that of the HE-LTF 825 for theSTA user 1. Advantageously, the receiver for the AP 104 can besimplified, and redundant HE-LTFs 825 can improve channel estimation.

In some embodiments, STAs can pad the length of each HE-LTF 825 to matchthe longest HE-LTF 825 across each zone, but not across the entirebandwidth. For example, the STA user 2 can pad its HE-LTF 825 to matchthe longest HE-LTF 825 in the OFDMA zone 845, but not to match theHE-LTF 825 for the user 1, which is in a different zone. Accordingly,overhead for OFDMA users can be low, and the receiver for the AP 104 canbe simplified.

In some embodiments, no STAs pay the length of the HE-LTF 825. Forexample, the STA user 2 can transmit a HE-LTF 825 that is shorter thanthe HE-LTF 825 of the STA user 1. Accordingly, overhead for the STA user1 transmission can be reduced.

FIG. 10 illustrates another exemplary structure of an uplinkphysical-layer packet 1000 which can be used to enable wirelesscommunications. In the illustrated embodiment, the physical-layer packet1000 includes the L-STF 422, L-LTF 426, the L-SIG 426, the HE-SIG0 815,the HE-STF 820, the HE-LTF 825, the HE-SIG1 830, and the payload 835. Aperson having ordinary skill in the art will appreciate that theillustrated physical-layer packet 800 can include additional fields,fields can be rearranged, removed, and/or resized, and the contents ofthe fields varied. As shown in FIG. 10, the HE-LTF 825 for the STA user2 is shorter than the HE-LTF 825 for the STA user 1, and the two are notaligned.

HE-SIG1 Field

Referring back to FIG. 8, in one embodiment, the packet 800 can omit theHE-SIG1 fields 830, thereby reducing overhead. In another embodiment,the packet 800 includes the HE-SIG1 fields 830. Including the HE-SIG1fields 830 can advantageously convey additional information (such as,for example, modulation and control scheme parameters, etc.).

FIG. 11 shows another flowchart 1100 for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem 110 of FIG. 1. The method can be implemented in whole or in partby the devices described herein, such as the wireless device 202 shownin FIG. 2. Although the illustrated method is described herein withreference to the wireless communication system 100 discussed above withrespect to FIG. 1 and the packets 800, 900A-900C, and 1000 discussedabove with respect to FIGS. 8-10, a person having ordinary skill in theart will appreciate that the illustrated method can be implemented byanother device described herein, or any other suitable device (such asthe STA 106 and/or the AP 104). Although the illustrated method isdescribed herein with reference to a particular order, in variousembodiments, blocks herein can be performed in a different order, oromitted, and additional blocks can be added.

First, at block 1110, a first wireless device generates a first packetincluding a first preamble decodable by a plurality of devices and asecond preamble decodable by only a subset of the plurality of devices.For example, the STA 106 can generate the packet 800, which can includethe legacy preamble 805 and the HE preamble 810. In various embodiments,the legacy preamble 805 can correspond to the first preamble and the HEpreamble 810 can correspond to the second preamble.

The first preamble includes a first signal field. For example, thelegacy preamble 805 includes the L-SIG 426, which can correspond to thefirst signal field. The second preamble includes a first training field.For example, the HE preamble 810 includes the HE-LTF 825, which cancorrespond to the first training field.

In various embodiments, the first signal field can include an immediateresponse presence and/or duration indication. In various embodiments,the first signal field can include a transmit power indication. Invarious embodiments, the first signal field can include a partial timesynchronization function (TSF).

In various embodiments, the first signal field can include a transmitopportunity (TXOP) bandwidth (BW) and/or primary channel offsetindication. In various embodiments, the first signal field can include apartial base station identifier (BSSID). In various embodiments, thefirst signal field can include a partial receiver association identifier(AID).

In various embodiments, the first signal field can include a partialtransmitter association identifier (AID). In various embodiments, thefirst signal field can include an uplink/downlink indication. In variousembodiments, the uplink/downlink indication can be implicit in atransmitter or receiver association identifier (AID).

Next, at block 1120, the wireless device transmits the first packetconcurrently with one or more second packets to be transmitted bywireless devices other than the first wireless device. For example, theSTA user 1 can transmit the UL packet 800 concurrently with the STA user2. The wireless device can transmit the first packet, for example, on adifferent physical or logical channel as the wireless devices other thanthe first wireless device. In some embodiments, the same channel can beused for at least a portion of the packet 800 (for example, the L-SIG426).

In various embodiments, the method can further include transmitting thefirst signal field over a channel bandwidth up to a full channelbandwidth size assigned to the first wireless device. For example, theSTA user 2 can be assigned only a portion of the lower 20 MHz channel(for example, 10 MHz), as illustrated in FIG. 8. The STA user 2 canround the assigned 10 MHz channel up to the nearest full channel size,for example 20 MHz. Thus, the user 2 can transmit the L-SIG 426 over thelower 20 MHz channel

In various embodiments, the method can further include, when the firstwireless device is not assigned use of a channel designated as a primarychannel, transmitting the first signal field over the channel designatedas the primary channel. For example, the STA user 2 can transmit theL-SIG 426 on the upper 20 MHz channel, in addition to the lower 20 MHzchannel to which it's assigned, when the upper 20 MHz channel is theprimary channel.

In various embodiments, the method can further include transmitting thefirst signal field over an available channel bandwidth including one ormore channels not assigned for use by the first wireless device. Invarious embodiments, the available channel bandwidth can be an entiretyof the available channel bandwidth. For example, the STA user 2 cantransmit the L-SIG 426 on all 40 MHz of available bandwidth.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a common zone with the first wirelessdevice. The method can further include setting the first signal field toindicate a length of the first packet equal to a length of a longest ofthe at least one second packet to be transmitted by the second wirelessdevice assigned to the common zone with the first wireless device. Themethod can further include padding the first packet for transmission toequal the length of the longest of the at least one second packet to betransmitted by the second wireless device assigned to the common zonewith the first wireless device.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device assigned to a different zone from the first wirelessdevice. The method can further include setting the first signal field toindicate a length of the first packet equal to a length of a longest ofthe at least one second packet to be transmitted by the second wirelessdevice being assigned to any zone including a commonly assigned zonewith the first wireless device. The method can further include paddingthe first packet for transmission to equal the length of the longest ofthe at least one second packet to be transmitted by the second wirelessdevice being assigned to any zone including a commonly assigned zonewith the first wireless device.

In various embodiments, a length of the first packet can be shorter thana length of at least one second packet to be transmitted by a secondwireless device. The method can further include the method can furtherinclude refraining from padding the first packet.

In various embodiments, the second preamble can further include a secondsignal field. For example, the HE preamble 810 can include the HE-SIG0field 815, which can correspond to the second signal field. In variousembodiments, the HE-SIG0 field 815 can be one symbol in length.

In various embodiments, the second preamble can further include a fullor partial repetition of the first signal field, and a second signalfield. For example, the HE preamble 810 can include the RL-SIG 910,which can correspond to the partial (or at least partial) repetition ofthe L-SIG 426. The HE preamble 810 can include the HE-SIG0 field 815,which can correspond to the second signal field. In some embodiments,the repetition of the first signal field can be included in the firstportion instead. In various embodiments, the second preamble can furtherinclude a repetition of even or odd tones of the first signal field, anda second signal field.

In various embodiments, the method can further include encoding one ormore bits in a polarity of the full or partial repetition of the firstsignal field. For example, to encode a 1, the STA 106 can multiply therepeated bits in the L-SIG 426 by −1, to encode a 0, the STA 106 canmultiply the repeated bits in the L-SIG 426 by 1, and so on. In variousembodiments, positive and negative repetition polarities can represent 0and 1, respectively. In other embodiments, different encodings arepossible.

In various embodiments, the second preamble can further include a secondsignal field and a repetition of the second signal field. For example,the HE preamble 810 can include the HE-SIG0 field 815, which cancorrespond to the second signal field. In various embodiments, thesecond preamble can further include a second training field, the secondtraining field shorter than the first training field. For example, theHE preamble 810 can include the RHE-SIG0 field 915, which can correspondto the repeated second signal field.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby the second wireless device assigned to the common zone with the firstwireless device. The method can further include padding the firsttraining field to align a boundary of all training fields to betransmitted by the second wireless device assigned to the common zonewith the first wireless device. For example, the STA user 2 can pad itsHE-LTF 825 to match the length of the HE-LTF 825 for another user in theOFDMA zone 845.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device being assigned to any zone including acommonly assigned zone with the first wireless device. The method canfurther include padding the first training field to align a boundary ofall training fields to be transmitted by a second wireless device beingassigned to any zone including a commonly assigned zone with the firstwireless device. For example, the STA user 2 can pad its HE-LTF 825 tomatch the length of the HE-LTF 825 for the STA user 1.

In various embodiments, a length of the first training field can beshorter than a length of at least one training field to be transmittedby a second wireless device. The method can further include refrainingfrom padding the first training field. In various embodiments, thesecond preamble can further include a third signal field. For example,the STA user 2 can refrain from padding the HE-LTF 825, as shown in FIG.10.

In an embodiment, the method shown in FIG. 11 can be implemented in awireless device that can include a generating circuit and a transmittingcircuit. Those skilled in the art will appreciate that a first wirelessdevice can have more components than the simplified wireless devicedescribed herein. The wireless device described herein includes onlythose components useful for describing some prominent features ofimplementations within the scope of the claims.

The generating circuit can be configured to generate the packet. In someembodiments, the generating circuit can be configured to perform atleast block 1110 of FIG. 11. The generating circuit can include one ormore of the processor 204 (FIG. 2), the memory 206 (FIG. 2), and the DSP220 (FIG. 2). In some implementations, means for generating can includethe generating circuit.

The transmitting circuit can be configured to transmit the packet. Insome embodiments, the transmitting circuit can be configured to performat least block 1120 of FIG. 11. The transmitting circuit can include oneor more of the transmitter 210 (FIG. 2), the antenna 216 (FIG. 2), andthe transceiver 214 (FIG. 2). In some implementations, means fortransmitting can include the transmitting circuit.

A person/one having ordinary skill in the art would understand thatinformation and signals can be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that can bereferenced throughout the above description can be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

Various modifications to the implementations described in thisdisclosure can be readily apparent to those skilled in the art, and thegeneric principles defined herein can be applied to otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the disclosure is not intended to be limited to theimplementations shown herein, but is to be accorded the widest scopeconsistent with the claims, the principles and the novel featuresdisclosed herein. The word “exemplary” is used exclusively herein tomean “serving as an example, instance, or illustration.” Anyimplementation described herein as “exemplary” is not necessarily to beconstrued as preferred or advantageous over other implementations.

Certain features that are described in this specification in the contextof separate implementations also can be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation also can be implemented inmultiple implementations separately or in any suitable sub-combination.Moreover, although features can be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination can be directed to asub-combination or variation of a sub-combination.

The various operations of methods described above can be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures can be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure can be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor can be a microprocessor, but in thealternative, the processor can be any commercially available processor,controller, microcontroller or state machine. A processor can also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

In one or more aspects, the functions described can be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions can be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media can be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can include RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Thus, in some aspects computer readable medium can includenon-transitory computer readable medium (e.g., tangible media). Inaddition, in some aspects computer readable medium can includetransitory computer readable medium (e.g., a signal). Combinations ofthe above can also be included within the scope of computer-readablemedia.

The methods disclosed herein include one or more steps or actions forachieving the described method. The method steps and/or actions can beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions can bemodified without departing from the scope of the claims.

Further, it can be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure can be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method of wireless communication, comprising:generating, at a first wireless device, a first packet comprising afirst preamble decodable by a plurality of devices and a second preambledecodable by only a subset of the plurality of devices, the firstpreamble comprising a first signal field, and the second preamblecomprising a first training field; and transmitting the first packetconcurrently with one or more second packets to be transmitted bywireless devices other than the first wireless device.
 2. The method ofclaim 1, further comprising transmitting the first signal field over achannel bandwidth up to a full channel bandwidth size assigned to thefirst wireless device.
 3. The method of claim 1, further comprising,when the first wireless device is not assigned use of a channeldesignated as a primary channel, transmitting the first signal fieldover the channel designated as the primary channel.
 4. The method ofclaim 1, further comprising transmitting the first signal field over anavailable channel bandwidth including one or more channels not assignedfor use by the first wireless device.
 5. The method of claim 4, whereinthe available channel bandwidth is an entirety of the available channelbandwidth.
 6. The method of claim 1, wherein: a length of the firstpacket is shorter than a length of at least one second packet to betransmitted by a second wireless device assigned to a common zone withthe first wireless device; and the method further comprises setting thefirst signal field to indicate a length of the first packet equal to alength of a longest of the at least one second packet to be transmittedby the second wireless device assigned to the common zone with the firstwireless device.
 7. The method of claim 6, the method further comprisingpadding the first packet for transmission to equal the length of thelongest of the at least one second packet to be transmitted by thesecond wireless device assigned to the common zone with the firstwireless device.
 8. The method of claim 1, wherein: a length of thefirst packet is shorter than a length of at least one second packet tobe transmitted by a second wireless device being assigned to any zoneincluding a commonly assigned zone with the first wireless device; andthe method further comprises setting the first signal field to indicatea length of the first packet equal to a length of a longest of the atleast one second packet to be transmitted by the second wireless devicebeing assigned to any zone.
 9. The method of claim 8, the method furthercomprising padding the first packet for transmission to equal the lengthof the longest of the at least one second packet to be transmitted bythe second wireless device being assigned to any zone including acommonly assigned zone with the first wireless device.
 10. The method ofclaim 1, wherein: a length of the first packet is shorter than a lengthof at least one second packet to be transmitted by a second wirelessdevice; and the method further comprises refraining from padding thefirst packet.
 11. The method of claim 1, wherein the second preamblefurther comprises a second signal field.
 12. The method of claim 1,wherein the second preamble further comprises a second signal field thatis one symbol in length.
 13. The method of claim 1, wherein the secondpreamble further comprises a full or partial repetition of the firstsignal field, and a second signal field.
 14. The method of claim 13,further comprising encoding one or more bits in a polarity of the fullor partial repetition of the first signal field.
 15. An apparatusconfigured to wirelessly communicate, comprising: a processor configuredto generate a first packet comprising a first preamble decodable by aplurality of devices and a second preamble decodable by only a subset ofthe plurality of devices, the first preamble comprising a first signalfield, and the second preamble comprising a first training field; and atransmitter configured to transmit the first packet concurrently withone or more second packets to be transmitted by wireless devices otherthan the apparatus.
 16. The apparatus of claim 15, wherein the secondpreamble further comprises a repetition of even or odd tones of thefirst signal field, and a second signal field.
 17. The apparatus ofclaim 15, wherein the second preamble further comprises a second signalfield and a repetition of the second signal field.
 18. The apparatus ofclaim 15, wherein the second preamble further comprises a secondtraining field, the second training field shorter than the firsttraining field.
 19. The apparatus of claim 15, wherein: a length of thefirst training field is shorter than a length of at least one trainingfield to be transmitted by a second wireless device assigned to a commonzone with the apparatus; and the processor is further configured to padthe first training field to align a boundary of all training fields tobe transmitted by the second wireless device assigned to the common zonewith the apparatus.
 20. The apparatus of claim 15, wherein: a length ofthe first training field is shorter than a length of at least onetraining field to be transmitted by a second wireless device beingassigned to any zone including a commonly assigned zone with theapparatus; and the processor is further configured to pad the firsttraining field to align a boundary of all training fields to betransmitted by the second wireless device being assigned to any zoneincluding a commonly assigned zone with the apparatus.
 21. The apparatusof claim 15, wherein: a length of the first training field is shorterthan a length of at least one training field to be transmitted by asecond wireless device; and the processor is further configured torefrain from padding the first training field.
 22. The apparatus ofclaim 15, wherein the second preamble further comprises a second signalfield, and may further comprise a repetition of the second signal fieldbased, at least in part, on one of: a protection method used for a thirdsignal field of the second portion; a compression method used for thefirst training field; and a prefix of a payload of the first packet. 23.The apparatus of claim 15, wherein the first signal field comprises animmediate response presence and/or duration indication.
 24. Theapparatus of claim 15, wherein the first signal field comprises atransmit power indication.
 25. The apparatus of claim 15, wherein thefirst signal field comprises a partial time synchronization function(TSF).
 26. The apparatus of claim 15, wherein the first signal fieldcomprises a transmit opportunity (TXOP) bandwidth (BW) and/or primarychannel offset indication.
 27. The apparatus of claim 15, wherein thefirst signal field comprises a partial base station identifier (BSSID).28. The apparatus of claim 15, wherein the first signal field comprisesan uplink/downlink indication.
 29. An apparatus for wirelesscommunication, comprising: means for generating a first packetcomprising a first preamble decodable by a plurality of devices and asecond preamble decodable by only a subset of the plurality of devices,the first preamble comprising a first signal field, and the secondpreamble comprising a first training field; and means for transmittingthe first packet concurrently with one or more second packets to betransmitted by wireless devices other than the apparatus.
 30. Anon-transitory computer-readable medium comprising code that, whenexecuted, causes an apparatus to: generate a first packet comprising afirst preamble decodable by a plurality of devices and a second preambledecodable by only a subset of the plurality of devices, the firstpreamble comprising a first signal field, and the second preamblecomprising a first training field; and transmit the first packetconcurrently with one or more second packets to be transmitted bywireless devices other than the apparatus.